The subject matter disclosed herein relates to communication systems, and more particularly, to systems and methods of conducting handoffs between voice encoders in a communication system.
A communication system may include devices capable of transmitting and receiving human speech. For example, a user may speak into a first communication device, and the speech waveform may be compressed and digitized and then transmitted to a second communication device. The compressed digital signal may be decompressed to reconstruct an approximation of the original speech waveform. The compression and decompression of speech signals in a communication system may involve voice encoders, commonly referred to as “vocoders.”
During a communication, users may communicate via communication devices which are linked to network nodes which may be connected within a communication network. The connection between a communication device and a particular network node may depend on signal quality parameters between the device and the node. As signal quality parameters may change during a communication, connection between a device and a node may sometimes be switched to maintain an acceptable signal quality. For example, a connection between a communication device and a first network node may be switched to enable a communication between the device and a second network node for improved signal quality. Such a switch in communication between device and network node may be referred to as a “handoff.”
Handoffs may occur substantially seamlessly when a communication device is switching from communicating with one network node using one type of vocoder to another network node using the same type of vocoder, as the architectures of the two vocoders may be similar, and the frames of the two like vocoders may be aligned in time. However, as communication systems have evolved, the number of different link layer technologies in a communication network has increased, potentially complicating the handoff process between different communication devices and different network nodes, as different communication technologies may use different types of vocoders for coding and decoding speech signals. Different vocoders may have different architectures with incompatible bit streams, different frame sizes, or different algorithmic delays, which decrease the likelihood of accomplishing an acceptable (e.g., substantially undetectable) handover. Thus, a more seamless method of performing a handoff in a communication system having different vocoders may improve communication quality.